Cannot go backwards in wizard

[kzamulin]

Code sample:

import { UseFilters, UseInterceptors } from '@nestjs/common';
import { Action, Ctx, Wizard, WizardStep } from 'nestjs-telegraf';
import { BotWizards } from 'src/common/enum/bot-wizards.enum';
import { TelegrafExceptionFilter } from 'src/common/filters/telegraf-exception.filter';
import { LoggingInterceptor } from 'src/common/interceptor/logger.interceptor';
import { TelegrafWizardContext } from 'src/common/interfaces/telegraf-wizard-context.interface';
import { Markup } from 'telegraf';
import { Update } from 'telegraf/typings/core/types/typegram';

@Wizard(BotWizards.Test)
@UseFilters(TelegrafExceptionFilter)
@UseInterceptors(LoggingInterceptor)
export class TestWizard {
  constructor() {}

  @WizardStep(1)
  protected async step1(@Ctx() ctx: TelegrafWizardContext) {
    await ctx.reply(
      'Step 1',
      Markup.inlineKeyboard([
        Markup.button.callback('Вперед', 'YES'),
        Markup.button.callback('Выход', 'EXIT')
      ])
    );
    ctx.wizard.next();
  }

  @WizardStep(2)
  @Action(['YES'])
  protected async step2(
    @Ctx() ctx: TelegrafWizardContext & { update: Update.CallbackQueryUpdate }
  ) {
    // await ctx.deleteMessage();
    await ctx.reply(
      'Step 2',
      Markup.inlineKeyboard([
        Markup.button.callback('Вперед', 'YES'),
        Markup.button.callback('Назад', 'BACK'),
        Markup.button.callback('Выход', 'EXIT')
      ])
    );
    ctx.wizard.next();
  }

  @WizardStep(3)
  @Action(['YES', 'BACK'])
  protected async step3(
    @Ctx() ctx: TelegrafWizardContext & { update: Update.CallbackQueryUpdate }
  ) {
    const reply = ctx.update.callback_query['data'];
    if (reply === 'YES') {
      // await ctx.deleteMessage();
      await ctx.reply(
        'Step 3',
        Markup.inlineKeyboard([
          Markup.button.callback('Вперед', 'YES'),
          Markup.button.callback('Назад', 'BACK'),
          Markup.button.callback('Выход', 'EXIT')
        ])
      );
      ctx.wizard.next();
    }
    if (reply === 'BACK') {
      // await ctx.deleteMessage();
      ctx.wizard.back();
      // @ts-ignore
      return ctx.wizard.steps[ctx.wizard.cursor](ctx);
    }
  }

  @WizardStep(4)
  @Action(['YES', 'BACK'])
  protected async step4(@Ctx() ctx: TelegrafWizardContext) {
    // await ctx.deleteMessage();
    await ctx.reply('Step 4, the last');
    ctx.scene.leave();
  }

  // @Action('BACK')
  // protected async back(@Ctx() ctx) {
  //   await ctx.deleteMessage();
  //   ctx.wizard.back();
  //   ctx.wizard.steps[ctx.wizard.cursor](ctx);
  // }

  @Action('EXIT')
  protected async exit(@Ctx() ctx) {
    ctx.deleteMessage();
    await ctx.reply(
      `Existing`,
      Markup.removeKeyboard()
    );
    ctx.scene.leave();
  }
}

Error: following part

ctx.wizard.steps[ctx.wizard.cursor](ctx)

gives error:

[Nest] 13954  - 03/10/2023, 9:01:01 PM   ERROR [TelegrafExceptionFilter] Handler is undefined
Error: Handler is undefined
    at Function.unwrap (/home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:445:19)
    at execute (/home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:473:42)
    at /home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:475:27
    at /home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:341:20
    at /home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:167:111
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async execute (/home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:474:17)
    at async /home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:475:21
    at async execute (/home/ubuntu/repos/telegram/node_modules/telegraf/lib/composer.js:474:17)

This hack ctx.wizard.steps[ctx.wizard.cursor](ctx) is used in order to previous step to execute and show reply and buttons, as ctx.wizard.back() is not enough.

Versions:

"nestjs-telegraf": "^2.6.3",
"@nestjs/core": "^9.0.0",
"telegraf": "^4.11.2"